
theorem Th938:
Sum digits(207,10) = 9
proof
  thus Sum digits(207,10) = Sum <%7,0%>+Sum <%2%> by Th937,AFINSQ_2:55
  .= (7 + 0) + Sum <%2%> by AFINSQ_2:54
  .= 7 + 2 by AFINSQ_2:53
  .= 9;
end;
